Since last fall, Toyota has recalled more than 8 million vehicles worldwide for problems involving sudden acceleration. Toyota has blamed the speed control issues on defective floor mats and faulty accelerator pedals, but some experts suspect that problems with the vehiclesâ€™ electronic throttle control system could really be behind the problems. Such suspicions have increased recently, as dozens of Toyota owners whose vehicles underwent recall repairs have recently complained that their vehicles are still experiencing problems with unintended acceleration.

As weâ€™ve reported previously, five deaths in the U.S. have occurred in auto accidents involving the unintended acceleration of a Toyota or Lexus vehicle. Last August, a California Highway Patrol trooper and three members of his family were killed in such a crash in San Diego County, just south of Orange. At least 47 other fatalities over the past decade alleged to be the result of Toyota unintended acceleration crashes are currently being investigated by the National Highway Traffic Safety Administration (NHTSA).

While the U.S. Department of Justice won’t say one way or another whether it’s investigating Toyota, the automaker has confirmed that such probes are underway. According to the Tribune, Toyota has said that it was served with a subpoena from a federal grand jury in New York in February that asked for “certain documents related to unintended acceleration of Toyota vehicles and the braking system of the Prius.” That investigation could ultimately result in criminal charges.

Toyota has also been served with a subpoena from the SEC, relating to unintended acceleration and “the company’s disclosure policies and practice,” The Chicago Tribune said.

Toyota has indicated that it intends to cooperate with both of the subpoenas.

The Los Angeles city attorney’s office also opened a Toyota investigation this month. Assistant City Attorney Jeffrey Isaacs, who is in charge of the probe, recently told myfoxla.com that if complaints about malfunctions can be verified, “the city attorney is authorized by state law to file an unfair competition law action on behalf of the people of the state of California in which he could seek injunctive relief, civil penalties — which could be very large in this instance, depending on the number of incidents — and also, most importantly, restitution for victims.”

The Los Angeles city attorney’s office is urging members of the public who bought Toyota or Lexus vehicles over the last 10 years to fill out a form on the city attorney’s Web site — atty.lacity.org — and describe any incidents of sudden unintended acceleration, braking or steering problems.